It's been said that parenting is the toughest job in the world. Wrong. It's the second toughest: Stepparenting wins hands down. Right now, approximately half of all Americans live in a stepfamily, which means that every day, millions of women are subject to the taunt—sometimes mournful, often angry—"You're not my mother!"

I've been a stepmother three times. I know, from hard-won experience, that a great relationship with your stepkids is possible. And if you avoid certain trapdoors like the 12 verboten phrases here, you'll not only get along, but you'll never have to ask them to pick up their socks.

Twelve ways to keep you in their good graces.